In known devices dedicated to a content processing, said content needing to be protected, security of said content is generally controlled by means external to the chip that process the content, called main chip in the following. Such external security means include smart card systems as, for example, described in document EP1150506. The advantage of such external security means is that they provide a good flexibility of the protection of the device.
Nevertheless, in this document, the chip that includes the content processing means, and consequently the core of the system, is not protected by itself. Connectors intended to be used to connect external elements like, for example, a bus for testing the chip, can serve to take control of the content processing means. Thus, the processed content is accessible and is no more protected. Moreover, separation between main chip and security elements implies that communications between the two can be eavesdropped. Moreover, security means proposed in the state of the art are expensive and require supplementary manufacturing steps to be implemented in devices.